The present invention relates to a rectilinear jack in which the stem of the jack can be blocked in any position between a minimum point and a maximum point.
Jacks are already known, used with various mechanisms related with seats, particularly motor vehicle seats, in order to provide, via a displacement of the jack stem, either a tilting of the seat back or a setting in height of the seat sitting portion, and some of them are even used as a seat slide for setting horizontally the position of a seat.
However, the use of such rectilinear jacks which has become general in the last years, is limited by the fact that, whatever their operation mode: that is hydraulic, blocked by jamming rings or using an endless screw and a screw-nut, their principles of implementation are costly because of the necessary quality requirements of their components.
The simple concept of the present invention consists in the use of an assembly of little accurate parts forming a rectilinear jack which can be blocked by rollers in any indifferent position between a minimum point and a maximum point, whereby the jack stem is mobile and the blocking device fixed or, reversely, the blocking device is mobile and the jack stem fixed.